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[clang-tidy] new check misc-use-internal-linkage (#90830)
Add new check misc-use-internal-linkage to detect variable and function can be marked as static. --------- Co-authored-by: Danny Mösch <danny.moesch@icloud.com>
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95 changes: 95 additions & 0 deletions
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clang-tools-extra/clang-tidy/misc/UseInternalLinkageCheck.cpp
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//===--- UseInternalLinkageCheck.cpp - clang-tidy--------------------------===// | ||
// | ||
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
// See https://llvm.org/LICENSE.txt for license information. | ||
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
// | ||
//===----------------------------------------------------------------------===// | ||
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#include "UseInternalLinkageCheck.h" | ||
#include "../utils/FileExtensionsUtils.h" | ||
#include "clang/AST/Decl.h" | ||
#include "clang/ASTMatchers/ASTMatchFinder.h" | ||
#include "clang/ASTMatchers/ASTMatchers.h" | ||
#include "clang/ASTMatchers/ASTMatchersMacros.h" | ||
#include "clang/Basic/SourceLocation.h" | ||
#include "clang/Basic/Specifiers.h" | ||
#include "llvm/ADT/STLExtras.h" | ||
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using namespace clang::ast_matchers; | ||
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namespace clang::tidy::misc { | ||
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namespace { | ||
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AST_MATCHER(Decl, isFirstDecl) { return Node.isFirstDecl(); } | ||
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static bool isInMainFile(SourceLocation L, SourceManager &SM, | ||
const FileExtensionsSet &HeaderFileExtensions) { | ||
for (;;) { | ||
if (utils::isSpellingLocInHeaderFile(L, SM, HeaderFileExtensions)) | ||
return false; | ||
if (SM.isInMainFile(L)) | ||
return true; | ||
// not in header file but not in main file | ||
L = SM.getIncludeLoc(SM.getFileID(L)); | ||
if (L.isValid()) | ||
continue; | ||
// Conservative about the unknown | ||
return false; | ||
} | ||
} | ||
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AST_MATCHER_P(Decl, isAllRedeclsInMainFile, FileExtensionsSet, | ||
HeaderFileExtensions) { | ||
return llvm::all_of(Node.redecls(), [&](const Decl *D) { | ||
return isInMainFile(D->getLocation(), | ||
Finder->getASTContext().getSourceManager(), | ||
HeaderFileExtensions); | ||
}); | ||
} | ||
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AST_POLYMORPHIC_MATCHER(isExternStorageClass, | ||
AST_POLYMORPHIC_SUPPORTED_TYPES(FunctionDecl, | ||
VarDecl)) { | ||
return Node.getStorageClass() == SC_Extern; | ||
} | ||
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} // namespace | ||
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void UseInternalLinkageCheck::registerMatchers(MatchFinder *Finder) { | ||
auto Common = | ||
allOf(isFirstDecl(), isAllRedeclsInMainFile(HeaderFileExtensions), | ||
unless(anyOf( | ||
// 1. internal linkage | ||
isStaticStorageClass(), isInAnonymousNamespace(), | ||
// 2. explicit external linkage | ||
isExternStorageClass(), isExternC(), | ||
// 3. template | ||
isExplicitTemplateSpecialization(), | ||
// 4. friend | ||
hasAncestor(friendDecl())))); | ||
Finder->addMatcher( | ||
functionDecl(Common, unless(cxxMethodDecl()), unless(isMain())) | ||
.bind("fn"), | ||
this); | ||
Finder->addMatcher(varDecl(Common, hasGlobalStorage()).bind("var"), this); | ||
} | ||
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static constexpr StringRef Message = | ||
"%0 %1 can be made static or moved into an anonymous namespace " | ||
"to enforce internal linkage"; | ||
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void UseInternalLinkageCheck::check(const MatchFinder::MatchResult &Result) { | ||
if (const auto *FD = Result.Nodes.getNodeAs<FunctionDecl>("fn")) { | ||
diag(FD->getLocation(), Message) << "function" << FD; | ||
return; | ||
} | ||
if (const auto *VD = Result.Nodes.getNodeAs<VarDecl>("var")) { | ||
diag(VD->getLocation(), Message) << "variable" << VD; | ||
return; | ||
} | ||
llvm_unreachable(""); | ||
} | ||
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} // namespace clang::tidy::misc |
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clang-tools-extra/clang-tidy/misc/UseInternalLinkageCheck.h
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//===--- UseInternalLinkageCheck.h - clang-tidy -----------------*- C++ -*-===// | ||
// | ||
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||
// See https://llvm.org/LICENSE.txt for license information. | ||
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
// | ||
//===----------------------------------------------------------------------===// | ||
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_USEINTERNALLINKAGECHECK_H | ||
#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_USEINTERNALLINKAGECHECK_H | ||
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#include "../ClangTidyCheck.h" | ||
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namespace clang::tidy::misc { | ||
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/// Detects variables and functions that can be marked as static or moved into | ||
/// an anonymous namespace to enforce internal linkage. | ||
/// | ||
/// For the user-facing documentation see: | ||
/// http://clang.llvm.org/extra/clang-tidy/checks/misc/use-internal-linkage.html | ||
class UseInternalLinkageCheck : public ClangTidyCheck { | ||
public: | ||
UseInternalLinkageCheck(StringRef Name, ClangTidyContext *Context) | ||
: ClangTidyCheck(Name, Context), | ||
HeaderFileExtensions(Context->getHeaderFileExtensions()) {} | ||
void registerMatchers(ast_matchers::MatchFinder *Finder) override; | ||
void check(const ast_matchers::MatchFinder::MatchResult &Result) override; | ||
std::optional<TraversalKind> getCheckTraversalKind() const override { | ||
return TK_IgnoreUnlessSpelledInSource; | ||
} | ||
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private: | ||
FileExtensionsSet HeaderFileExtensions; | ||
}; | ||
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} // namespace clang::tidy::misc | ||
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_USEINTERNALLINKAGECHECK_H |
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27 changes: 27 additions & 0 deletions
27
clang-tools-extra/docs/clang-tidy/checks/misc/use-internal-linkage.rst
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.. title:: clang-tidy - misc-use-internal-linkage | ||
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misc-use-internal-linkage | ||
========================= | ||
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Detects variables and functions that can be marked as static or moved into | ||
an anonymous namespace to enforce internal linkage. | ||
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Static functions and variables are scoped to a single file. Marking functions | ||
and variables as static helps to better remove dead code. In addition, it gives | ||
the compiler more information and allows for more aggressive optimizations. | ||
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Example: | ||
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.. code-block:: c++ | ||
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int v1; // can be marked as static | ||
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void fn1(); // can be marked as static | ||
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namespace { | ||
// already in anonymous namespace | ||
int v2; | ||
void fn2(); | ||
} | ||
// already declared as extern | ||
extern int v2; |
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clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func.h
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#pragma once | ||
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void func_header(); | ||
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#include "func_h.inc" |
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clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func_cpp.inc
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void func_cpp_inc(); |
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clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/func_h.inc
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void func_h_inc(); |
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clang-tools-extra/test/clang-tidy/checkers/misc/Inputs/use-internal-linkage/var.h
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#pragma once | ||
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extern int gloabl_header; |
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clang-tools-extra/test/clang-tidy/checkers/misc/use-internal-linkage-func.cpp
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// RUN: %check_clang_tidy %s misc-use-internal-linkage %t -- -- -I%S/Inputs/use-internal-linkage | ||
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#include "func.h" | ||
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void func() {} | ||
// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func' | ||
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template<class T> | ||
void func_template() {} | ||
// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func_template' | ||
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void func_cpp_inc(); | ||
// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'func_cpp_inc' | ||
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#include "func_cpp.inc" | ||
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void func_h_inc(); | ||
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struct S { | ||
void method(); | ||
}; | ||
void S::method() {} | ||
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void func_header(); | ||
extern void func_extern(); | ||
static void func_static(); | ||
namespace { | ||
void func_anonymous_ns(); | ||
} // namespace | ||
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int main(int argc, const char*argv[]) {} | ||
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extern "C" { | ||
void func_extern_c_1() {} | ||
} | ||
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extern "C" void func_extern_c_2() {} |
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clang-tools-extra/test/clang-tidy/checkers/misc/use-internal-linkage-var.cpp
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// RUN: %check_clang_tidy %s misc-use-internal-linkage %t -- -- -I%S/Inputs/use-internal-linkage | ||
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#include "var.h" | ||
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int global; | ||
// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: variable 'global' | ||
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template<class T> | ||
T global_template; | ||
// CHECK-MESSAGES: :[[@LINE-1]]:3: warning: variable 'global_template' | ||
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int gloabl_header; | ||
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extern int global_extern; | ||
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static int global_static; | ||
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namespace { | ||
static int global_anonymous_ns; | ||
namespace NS { | ||
static int global_anonymous_ns; | ||
} | ||
} | ||
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static void f(int para) { | ||
int local; | ||
static int local_static; | ||
} | ||
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struct S { | ||
int m1; | ||
static int m2; | ||
}; | ||
int S::m2; | ||
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extern "C" { | ||
int global_in_extern_c_1; | ||
} | ||
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extern "C" int global_in_extern_c_2; |